Further refinements will be carried out on new gas chromatographic assays of valproic acid (VPA) and carbamazepine (CBZ) developed during year 01. Studies will be made of the degradation and rearrangement products that occur when CBZ is subjected to the gas chromatographic on-column methylation technique. Studies are planned for developing gas chromatographic techniques for determining concentrations in urine of minor phenytoin (PHT) metabolites. Authentic specimens of the PHT metabolites and samples of appropriate internal standards will be synthesized as required. Other proposed plans for year 02 include, (1) the synthesis and studies of new on-column alkylation reagents, and (2) studies of the limitations of the OCMT in automated gas chromatography.